Orthopedic tools for implantation

ABSTRACT

The present application is generally directed to improved instruments and instrument features for distraction and tissue retraction. In particular, the present application is directed to distraction blades and wide blocking blades that can be used together, or individually, to assist in the distraction of bone and the retraction of tissue during a surgical procedure, such as a spinal fusion procedure.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/482,963, filed on Sep. 23, 2021, which is a continuation of U.S.patent application Ser. No. 16/529,840 filed on Aug. 2, 2019, which is acontinuation of U.S. application Ser. No. 14/519,961, filed on Oct. 21,2014 (U.S. Pat. No. 10,426,454), all of which are hereby incorporated byreference in their entirety for all purposes.

FIELD OF THE INVENTION

The present application is generally directed to improved instrumentsand instrument features for distraction and tissue retraction.

BACKGROUND

Spinal fusion procedures are performed on patients to treat lower backpain caused by degenerated discs. During spinal fusion procedures, asurgeon restores a disc space back to its original height beforeinserting an interbody fusion device and graft material into the discspace. To accomplish this, a surgeon uses a distraction instrument toseparate adjacent bones. To access the surgical site, a surgeon retractstissue. The tissue retraction is performed by a retraction instrumentthat is separate from the distraction instrument.

There is a need for tools to better serve the purpose of both bonedistraction and tissue retraction.

SUMMARY OF THE INVENTION

The present application is generally directed to improved instrumentsand instrument features for distraction and tissue retraction. In someembodiments, an orthopedic system comprises a first bone pin, whereinthe first bone pin comprises a lower threaded portion and an upperthreaded portion; a first wide blocking blade delivered over the firstbone pin, wherein the first wide blocking blade comprises at least twoblocking panels; a first distraction blade delivered over the first bonepin, wherein the first distraction blade includes a slot for receivingthe first bone pin therein; a second bone pin, wherein the second bonepin comprises a lower threaded portion and an upper threaded portion; asecond wide blocking blade delivered over the second bone pin, whereinthe second wide blocking blade comprises at least two blocking panels; asecond distraction blade delivered over the second bone pin, wherein thesecond distraction blade includes a slot for receiving the second bonepin therein; and a frame attached to at least one of either: (i) thefirst distraction blade and the second distraction blade or (ii) thefirst wide blocking blade and the second wide blocking blade.

In other embodiments, the orthopedic system comprises a first bone pin;a first wide blocking blade delivered over the first bone pin; a firstdistraction blade delivered over the first bone pin, wherein the firstdistraction blade includes a slot for receiving the first bone pintherein; a second bone pin; a second wide blocking blade delivered overthe second bone pin; a second distraction blade delivered over thesecond bone pin, wherein the second distraction blade includes a slotfor receiving the second bone pin therein; and a frame attached to atleast one of either: (i) the first distraction blade and the seconddistraction blade or (ii) the first wide blocking blade and the secondwide blocking blade.

In other embodiments, the orthopedic system comprises a first bone pin;a first wide blocking blade delivered over the first bone pin; a secondbone pin; a second wide blocking blade delivered over the second bonepin; and a frame attached to the first wide blocking blade and thesecond wide blocking blade.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a system including pair of distraction blades attached tovertebral bodies in accordance with some embodiments.

FIG. 2 shows a different view of the distraction blades of FIG. 1 .

FIG. 3 shows a system including a pair of distraction blades withintegrated bone pins in accordance with some embodiments.

FIG. 4 shows a distraction blade separated from an integrated bone pinin accordance with some embodiments.

FIG. 5 shows an alternative distraction blade and integrated bone pin inaccordance with some embodiments.

FIG. 6 shows the distraction blade of FIG. 5 .

FIG. 7 shows a bone pin in accordance with some embodiments.

FIGS. 8A and 8B show different views of a frame in accordance with someembodiments.

FIG. 9 shows an alternative distraction blade having a ball-socketconnection with integrated bone pin in accordance with some embodiments.

FIG. 10 shows a rear view of a distraction blade having a ball-socketconnection with bone pin in accordance with some embodiments.

FIG. 11 shows an alternative distraction blade and jointed bone pin inaccordance with some embodiments.

FIG. 12 shows a distraction blade with integrated jointed bone pin inaccordance with some embodiments.

FIG. 13 shows a system including a pair of wide blocking blades inaccordance with some embodiments.

FIG. 14 shows a top view of the system including a pair of wide blockingblades of FIG. 13 .

FIG. 15 shows a pair of wide blocking blades in accordance with someembodiments.

FIGS. 16-21 show a method of assembly of one or more wide blockingblades in conjunction with one or more distraction blades in accordancewith some embodiments.

FIG. 22 shows a pair of wide blocking blades in use with a frame inaccordance with some embodiments.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present application is generally directed to improved instrumentsand instrument features for distraction and tissue retraction. Inparticular, the present application describes spine surgery instrumentsthat are capable of both distraction and tissue retraction, therebyadvantageously removing the need to use multiple instruments duringspinal procedures.

During spinal fusion procedures, a surgeon restores a disc space back toits original height before inserting an interbody fusion device andgraft material into the disc space. To accomplish this heightrestoration, a surgeon uses a distraction instrument to separateadjacent bones. In order to access the surgical site to perform thedistraction, a surgeon must retract tissue to provide a pathway to thesite. The tissue retraction is performed using a retraction instrumentthat is typically separate from the distraction instrument.

One common type of spine procedure is an ACDF procedure. In the last tenyears, the number of ACDF procedures has more than doubled, with therate of success being quite high. Despite the high success rate,improvements are still needed. Studies have found that the incidence ofdysphagia after ACDF can be quite high, with reports showing that up to47% of patients experience short-term swallowing dysfunction, withpossibly more going unreported. It is believed that the presence ofdysphagia is related to the force applied by ACDF retractors againstsurrounding soft tissue, dissection of the longus coli muscle, as wellas intubation tubing. Additional concerns arise during the ACDFprocedures themselves, when delays may occur from constant shifting ofthe typical self-retaining retractors and difficulty in visibilityarises from the clutter of retractor frames used alongside separatedistracters, all within what is intended to be the smallest incisionrequired.

The present application is directed to instruments and instrumentfeatures that reduce the likelihood of dysphagia and other side-effectsthat may occur during ACDF procedures. The instruments described hereincan be used to both retract tissue and distract vertebral bodies totheir original height, thereby reducing the need to use separateinstruments and increasing visibility to a surgical site. By providinginstruments that can both retract tissue and distract vertebrae, tissuecan be protected during the distraction process, thereby reducing therisk of dysphagia to a patient. While the instruments described hereinare illustrated with respect to an ACDF procedure, one skilled in theart will appreciate that the instruments can be applied to othervertebral members as well, including in the thoracic, lumbar and sacralregions.

FIGS. 1 and 2 show different views of a surgical system comprising apair of novel distractor blades that are capable of both bonedistraction and tissue retraction in accordance with some embodiments.Each of the distraction blades 10 is associated with an integratedthreaded bone pin 25 that is positioned through a bone member. As shownin FIG. 1 , a first bone pin 25 is inserted into a first or uppervertebra 2, while the other bone pin 25 is inserted into a second orlower vertebra 3. In some embodiments, the installation of the bone pins25 into the bone members can occur prior to delivering the distractionblades 10 to the bone pins 25. With the bone pins 25 in place, thedistraction blades 10 can be positioned downwardly over and around thebone pins 25 via slots 18. The distraction blades 10 can rest on awasher, flange, protrusion or shelf feature 32 (shown in FIG. 7 ) of thebone pins 25, prior to securing the distraction blades to the bone pins25 via locking nuts 29 (also shown in FIG. 7 ) in preparation fordistraction. If some embodiments, the locking nuts 29 can be appliedloosely to secure the distraction blades 10 to the bone pins 25, therebyallowing angulation and wanding to provide more room for additionalinstrumentation during the surgical procedure. Advantageously, thedistraction blades 10 retract tissue as they are being inserted towardthe bone pins 25, and can continue to retract tissue once secured to thebone pins.

With the two distraction blades 10 in place with the integrated bonepins 25 as shown in FIGS. 1 and 2 , the distraction blades 10 arecapable of distracting the adjacent vertebral bodies to restore discheight. Distraction can occur via hand or via instrument. In someembodiments, one or more instruments for distraction can be attached tothe attachment portions 19 that are provided on each of the distractionblades 10. In some embodiments, a frame 50, as shown in FIGS. 8A and 8B,can be attached to the distraction blades 10, with a first arm 51 of theframe 50 attached to a first distraction blade 10 and a second arm 52attached to a second distraction blade 10. The frame 50 can include amechanism (e.g., a ratcheting mechanism) that can help the distractionblades 10 to distract the adjacent vertebral bodies. As such, the twodistraction blades 10 can advantageously be used for distraction, whilecontinuing to retract tissue, thereby reducing the need for separatedistraction and retraction instruments. Individual components of thesurgical system including the distraction blades and integrated pins arediscussed in more detail below.

FIG. 3 shows a system including a pair of distraction blades withintegrated bone pins in accordance with some embodiments. Each of thedistraction blades 10 includes a body 16 having an upper portion and alower portion. The upper portion of the body 16 includes a flattenedsection from which an attachment portion 19 extends or protrudes. Theattachment portion 19 is capable of attachment to a frame or otherinstrument for stabilization, retraction and/or distraction. The upperportion of the body 16 slopes downwardly into a flared lower portionthat includes an opening or slot for accepting a bone pin 25therethrough. In the present embodiment, a hoop or ring element 17(shown better in FIGS. 4 and 6 ) extends outwardly from the flared lowerportion. The ring element 17 can be designed to both receive theintegrated bone pin 25 and rest on the bone pin's shelf feature 32,shown in FIG. 7 .

Once a distraction blade 10 receives a bone pin 25, a locking nut 29(shown in FIG. 7 ) can be downwardly threaded onto the bone pin 25 tosecure the distraction blade 10 and bone pin 25. In some embodiments,the locking nut 29 is downwardly threaded but not tightened completelyso that the distraction blade 10 is capable of angling or wanding. Inother embodiments, the locking nut 29 is downwardly threaded andtightened completely so that the distraction blade 10 is fixed and notcapable of wanding. In some embodiments involving a pair of distractionblades 10, either blade can be fixed and/or capable of wanding.Regardless of whether the locking nut 29 is threaded downwardly andtightened completely or partially, the distraction blade 10 will beattached to the bone pin 25. At that point, when two or more distractionblades 10 are attached to their respective bone pins, a distractioninstrument can be attached to both so as to distract a first vertebralbody from another.

FIG. 4 shows a distraction blade separated from an integrated bone pinin accordance with some embodiments. From this view, one can see how thebody 16 of the distraction blade 10 has an upper portion with aflattened surface from which an attachment portion 19 extends, and alower flared out portion that extends from the upper portion. The lowerflared out portion tapers outwardly such that a distal most end of thedistraction blade 10 is the widest portion of the blade 10. The flaredshape of the distraction blade 10 is unique and allows it to contour tothe vertebral body, which allows for more secure positioning with theintegrated bone pin 25. As shown in FIG. 4 , the slot 18 that extendsthrough the body 16 of the blade can also have a flared portion thatgets wider toward a more distal end of the distraction blade 10. Thiswidening of the slot 18 advantageously allows the pin 25 to be easierreceived within the distraction blade 10.

In FIG. 4 , the bone pin 25 is shown separately from the distractionblade 10. The bone pin 25 is comprised of two different components—athreaded post 27 and a locking nut 29. In some embodiments, the threadedpost 27 can have one or more threads that extend along a length of itsbody. As shown in FIG. 7 , the threaded post 27 can have multiplethreads with different pitches. These threads will be discussed below.In addition to the threads, the threaded post 27 can have a washer,flange, protrusion or shelf portion 32 on which the ring element 17 ofthe distraction blade 10 can reside on prior to downwardly threading thelocking nut 29. As shown in FIG. 4 , the locking nut 29 is a separatecomponent from the threaded post 27, and includes internal threads tothread down the threaded post 27.

FIG. 5 shows an alternative distraction blade and integrated bone pin inaccordance with some embodiments, while FIG. 6 just shows thedistraction blade. The distraction blade 10 is similar to the bladeabove and includes a body 16 having an upper flattened portion with anattachment portion 19 extending therefrom; a downwardly flared portionincluding a slot 18; and a ring element 17 that extends outwardly fromthe downwardly flared portion. In contrast to the prior embodiment,however, the slot 18 is not flared open, but rather, maintains acontinuous width down the length of the distraction blade 10. Regardlessof the shape distinction, any of the slots 18 from the differentembodiments advantageously allow the distraction blade 10 to beside-loaded if desired onto an inserted bone pin 25. In addition, thedistraction blade 10 can also be top-loaded if desired onto an insertedbone pin 25 by, for example, depositing the ring element 17 over thebone pin 25. From these views, one can see the distinct contour of thebody 16 of the distraction blade 10. As shown in the figures, startingfrom the top flattened portion of the distraction blade 10, the body 16is tapered and flares outwardly such that a distal portion 9 of thedistraction blade 10 is wider than a proximal portion 7 of thedistraction blade.

FIG. 7 shows a bone pin in accordance with some embodiments. The bonepin 25 can be used with any of the distraction blades described herein.The bone pin 25 comprises two components—a threaded post 27 and alocking nut 29. As shown in FIG. 7 , the threaded post 27 comprises anupper section separated from a lower section by flanged shelf portion32. The lower section of the threaded post 27 includes lower threads 36to help drive the threaded post 27 into bone. The upper section of thethreaded post 27 includes a first set of upper threads 35 and a secondset of upper threads 38 separated by a smooth break portion 28. Thefirst set of upper threads 35 is positioned closer to a distal end ofthe threaded post 27 than the second set of upper threads 38. The firstset of upper threads 35 and second set of upper threads 38 are similarthreads that enable the locking nut 29 to be downwardly threadedthereon. Advantageously, the first set of upper threads 35 and secondset of upper threads 38 are separated by a smooth break 28, which helpsthe locking nut 29 to be downwardly deposited quicker, as it can easilytraverse the smooth break 28 without threading.

As shown in FIG. 7 , a locking nut 29 can be downwardly threaded ontothe threaded post 29. The locking nut 29 comprises a drive opening 39for receiving a drive instrument. In some embodiments, the drive opening39 comprises a hex opening for receiving a hex screw driver.

FIGS. 8A and 8B show different views of a frame in accordance with someembodiments. The frame 50 comprises a first arm 51 for gripping anattachment portion 19 of a first distraction blade 10 and a second arm52 for gripping an attachment portion 19 of a second distraction blade10. The frame 10 includes a table mount attachment portion 64 forattaching a table mount thereto. The frame 10 includes a linearlyactuating, ratcheting mechanism 65. To actuate the ratcheting mechanism65, the knob 61 can be rotated (e.g., via optional butterfly key 62).The use of the butterfly key 62 advantageously allows for controlledmovement of the ratcheting mechanism 65 in one direction. To move theratcheting mechanism 65 in an opposite direction, a surgeon can press onthe latch 67, which releases from the ratcheting teeth and allows foropposite movement.

With the first distraction blade 10 attached to the first arm 51 and thesecond distraction blade 10 attached to the second arm 52, the frame 50is capable of applying a force to separate the first distraction blade10 from the second distraction blade 10, thereby distraction adjacentvertebral bodies. In some embodiments, two or more frames 50 can bestacked on top of another, to cause an incision side to open in 2, 3, 4or more directions. In some embodiments, top-loading handheld adaptorscan also be provided to retain the distraction blades 10 prior to orafter attachment of the frame 50.

FIG. 9 shows an alternative distraction blade having a ball-socketconnection with integrated bone pin in accordance with some embodiments.FIG. 10 shows a rear view of the distraction blade. In theseembodiments, the distraction blade 110 comprises a body 116 having anupper flattened portion with an attachment portion 119 extendingtherefrom and a lower sweeping portion. The distal portion of thedistraction blade 110 comprises a ball-socket connection 117 forreceiving a head of a threaded post 127 therein. In contrast toembodiments in which the distraction blade 10 includes a ring element 17and a locking nut 29 to secure the blade 10 to the threaded post 27, inthe present embodiment, the threaded post 127 can be attached to theball-socket connection 117 via a snap fit.

As shown in FIG. 10 , the threaded post 127, which is shown with arounder, more spherical head, can be inserted into a rear opening 113formed in on a backside of the distraction blade 110, to securely snapinto the distraction blade 110. Advantageously, as the head of thethreaded post 127 is rounded, the distraction blade 110 can bepolyaxially adjusted around the threaded post 116, thereby allowingangling and wanding of the blade 110 during distraction and retraction.After inserting a first threaded post 127 into a first vertebral bodyand a second threaded post 127 into a second vertebral body, a firstdistraction blade 110 can be snap-fitted to the first threaded post 127,while a second distraction blade 110 can be snap-fitted to the secondthreaded post 127. With the pair of blades in position, an instrument(e.g., the frame in FIGS. 8A and 8B) can be attached to the blades 110to advantageously retract tissue and distract bone members using thesame instrument.

FIGS. 11 and 12 shows an alternative distraction blade and jointed bonepin in accordance with some embodiments. The distraction blade 210comprises a body 216 having an upper portion with an attachment portion219 extending therefrom and a lower portion that is tapered and flaresoutwardly. The lower portion of the blade 210 includes a slotted sleeveor shim 217 for receiving a jointed bone pin 225 therethrough.

The jointed bone pin 225 comprises two components—a threaded post 227and a locking nut 229. The threaded post 227 comprises a distallythreaded portion 236 for threading into bone. In a section that isproximal to the distally threaded portion 236, the threaded post 227advantageously includes a jointed portion 235 that allows the threadedpost 227 to bend and angle, even after it has been received through theslotted sleeve 217. In some embodiments, the distraction blade 210 withthe slotted shim 217 is top-loaded over the threaded post 227. Once thedistraction blade 210 is received over the threaded post 227, thelocking nut 229 can be downwardly threaded onto the threaded post 227.The downward threading of the locking nut 229 causes the distractionblade 210 to compress further down the threaded post 227, and securesthe distraction blade 210 to the threaded post 227 by preventing backoutof the blade 210.

Advantageously, even after the distraction blade 210 is attached to thethreaded post 227, the jointed portion 235 allows for angling andwanding of the distraction blade 210, thereby accommodating larger oradditional instruments during distraction and retraction. In someembodiments, the distraction blade 210 is capable of angling and wandinguntil the locking nut is tightly threaded 229 down the threaded post227. In some embodiments, the slotted shim or sleeve 217 can also bejointed to accommodate angling and wanding of the distraction blade 210.Accordingly, in some embodiments, the threaded post 227 and/or theslotted shim or sleeve 227 can be jointed to accommodate angling orwanding of the distraction blade 210.

As in the embodiments above, the distraction blade 210 can include anattachment portion 219 for attaching to a retraction and/or distractioninstrument, such as the frame shown in FIGS. 8A and 8B. In someembodiments, a first distraction blade 210 can be positioned over afirst jointed post 227 and a second distraction blade 210 can bepositioned over a second jointed post 227. A first locking nut 229 canbe downwardly deposited to secure the first distraction blade 210 to thefirst jointed post 227 in a fixed position, while a second locking nut229 can be downwardly deposited to secure the second distraction blade210 to the second jointed post 227. A frame 50 (as shown in FIGS. 8A and8B) can be attached to each of the first distraction blade 210 and thesecond distraction blade 210. The frame 50 can be linearly ratcheted,thereby causing the first distraction blade 210 to be pulled away fromthe second distraction blade 210, hence causing distraction of adjacentvertebral bodies. Advantageously, the blades 210 also retract tissue andmaintain an opening for instruments and implants to be inserted betweenthe blades 210 during the surgical process.

As discussed above, surrounding tissue can be injured or damaged duringboth tissue retraction and bone distraction. While the distractionblades 210 described above are designed to perform both distraction andretraction, thereby reducing the need for additional instruments andincreasing visibility of a surgical site to prevent tissue damage,additional protection of surrounding tissues may be desired. To provideadditional protection to surrounding tissue, one or more wide blockingblades can be provided. These blades can be used advantageously on theirown or with the distraction blades described above to provide protectionto surrounding tissue.

FIG. 13 shows a surgical system comprising a pair of wide blockingblades in accordance with some embodiments. FIG. 14 shows a top view ofthe wide blocking blades. The wide blocking blades 350 advantageouslyretract tissue and provide protection to surrounding tissue during asurgical procedure, particularly in a medial-to-lateral direction.Advantageously, the wide blocking blades 350 can be attached to the bonepins 25 described above, such that they can be used in conjunction withany of the distraction blades described above.

In some embodiments, each of the wide blocking blades 350 comprises afirst blocking panel 354, a transition panel 355 and a second blockingpanel 356. The first blocking panel 354 comprises a substantially flatwall (shown in FIG. 14 ) that is attached to a bone pin receiver 366.The bone pin receiver 366 comprises a ring or annular member that iscapable of sliding along the shaft of the bone pin 25, until it rests ona shelf portion of the bone pin 25 (as shown in FIG. 15 ). In theconfiguration of FIG. 14 , the first blocking panel 354 can protecttissue, particularly in the cephalad-to-caudal direction. Adjacent thefirst blocking panel 354 is a curved transition panel 355. The curvedtransition panel 355 comprises a curved wall that connects the firstblocking panel 354 to the second blocking panel 356. Advantageously, thecurved transition panel 355 can also serve as a blocking wall thatprotects tissue from damage during a surgical procedure. On the otherside of the curved transition panel 355 is a second blocking panel 356,which is wider than the first blocking panel 354. In the configurationof FIG. 14 , the second blocking panel 356 can protect tissue,particularly in the medial-to-lateral direction. An attachment section359 for attaching to another instrument (e.g., a frame 50) can be foundon an upper surface of the second blocking panel 356.

In some embodiments, one or more of the panels can include openings,windows or fenestrations 377 (shown in FIG. 13 on the second blockingpanels 356). These fenestrations 377 are optional and are designed tolessen any potential damage with surrounding tissue. As shown in FIG. 13, the fenestrations 377 can be formed in an up to down direction alongthe panel walls; however, in other embodiments, the fenestrations can beformed in a sideways direction or in any other shape or pattern.

The wide blocking blades 350 can advantageously be used on their own, orwith any of the distraction blades discussed above. A method ofassembling one or more wide blocking blades 350 with one or moredistraction blades 10 will now be described.

FIG. 15 shows a pair of wide blocking blades in accordance with someembodiments. Each of the wide blocking blades 350 comprise a firstblocking panel 354, a transition panel 355 and a second blocking panel356. A bone pin receiver 366 extends outwardly from the first blockingpanel 354. From this view, one can see how the bone pin receiver 366 isslidably received around the bone pin 25 until it resides on a distalportion of the bone pin 25. In some embodiments, the bone pin receivers366 can be of a certain internal shape (e.g., hexagonal) such that thewide blocking blades 350 do not rotate once they are deposited on thebone pins 25.

FIGS. 16-21 show a method of assembly of a system of one or more wideblocking blades in conjunction with one or more distraction blades inaccordance with some embodiments. In some embodiments, a method ofassembly of a system of one or more wide blocking blades comprises thefollowing:

-   -   (i) Begin by forming a slightly off-midline incision. Using a        handheld retractor, retract tissue in the medial-lateral        direction.    -   (ii) Insert first and second bone pins 25 (shown in FIG. 16 )        into the center of the vertebral body above and below the target        disc level. At this point, the locking nuts associated with the        bone pins 25 should be removed before inserting the bone pins 25        to enable wide blocking blades and/or distraction blades to be        delivered onto the bone pins 25.    -   (iii) Position a first wide blocking blade 350 over the first        bone pin 25 to retract tissue in the medial-to-lateral        direction, as shown in FIG. 17 . A second wide blocking blade        350 can be positioned over the second bone pin 25 to retract        tissue in the medial-to-lateral direction. If no        cephalad-to-caudal tissue retraction is required, first and        second locking nuts can be threaded down the bone pins 25 to        secure the wide blocking blades 350 in place. In some        embodiments, if desired, two wide blocking blades 350 can be        placed on the same bone pin 25 to retract alternate sides. This        can be particularly useful for multi-level ACDFs.        Advantageously, no longus muscle dissection is required for the        procedure described herein, thereby reducing risk of injury or        trauma to a patient.    -   (iv) If desired, a first distraction blade 10 can also be        delivered down the first bone pin 25 over the first wide        blocking blade 350, as shown in FIG. 19 . The distraction blade        10 can be positioned at a different angle from the wide blocking        blade 350. While the wide blocking blade 350 can retract tissue        in one direction (e.g., in a medial-to-lateral direction), the        distraction blade 10 can advantageously retract tissue and        assist in bone distraction in a different direction (e.g., in a        cephalad-to-caudal direction). The same assembly can be formed        with respect to the second bone pin 25, thereby creating a        retraction and distraction system with at least four walls.    -   (v) With the distraction blades 10 and wide blocking blades 350        in place over the bone pins 25, locking nuts 29 can be delivered        down the bone pins 25 to secure the assemblies, as shown in        FIGS. 20-21 .    -   (iv) At this point, one or more frames 50 (as shown in FIGS. 8A        and 8B) can be attached to the assembled system of bone pins 25.        The one or more frames 50 are capable of distracting vertebrae        in one or more directions.

While the embodiments described above show the wide blocking blades 350in use with one or more distraction blades, in some embodiments, thedistraction blades need not be added. FIG. 22 shows a pair of wideblocking blades 350 without the addition of the distraction bladesdiscussed above. The wide blocking blades 350 are connected to a frame50 which can be used to hold the wide blocking blades 350 apart asneeded. This creates a space in between the wide blocking blades 350 forsurgical instruments to be inserted therethrough.

The various systems described above, including those that comprise oneor more distraction blades and wide blocking blades, can assist invarious spinal procedures. In particular, fusion procedures, such asACDF procedures, can benefit from the use of the systems describedabove. The systems described above can provide access to surgical sitessuch that implants, such as cages and spacers (both expandable andnon-expandable), as well as graft material, can be inserted with ease.In addition, the systems described above can be used with a number ofother implants including, but not limited to, stabilization members(such as rods, hook members and bone screws, including occipital platesystems), prosthetic members (including prosthetic discs), and variousother spinal devices.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Moreover,the improved bone screw assemblies and related methods of use need notfeature all of the objects, advantages, features and aspects discussedabove. Thus, for example, those skilled in the art will recognize thatthe invention can be embodied or carried out in a manner that achievesor optimizes one advantage or a group of advantages as taught hereinwithout necessarily achieving other objects or advantages as may betaught or suggested herein. In addition, while a number of variations ofthe invention have been shown and described in detail, othermodifications and methods of use, which are within the scope of thisinvention, will be readily apparent to those of skill in the art basedupon this disclosure. It is contemplated that various combinations orsubcombinations of these specific features and aspects of embodimentsmay be made and still fall within the scope of the invention.Accordingly, it should be understood that various features and aspectsof the disclosed embodiments can be combined with or substituted for oneanother in order to form varying modes of the discussed bone screwassemblies. Thus, it is intended that the present invention cover themodifications and variations of this invention provided that they comewithin the scope of the appended claims or their equivalents.

What is claimed is:
 1. A tissue distraction system comprising: adistraction blade configured to distract tissue; a bone pin including: alower threaded portion adapted to be inserted into a vertebral body; aflange disposed above the lower threaded portion and adapted to supportthe distraction blade; an upper threaded portion disposed above theflange, wherein the distraction blade is adapted to be delivered overthe bone pin and shaped to rest on the flange.
 2. The system of claim 1,wherein the upper threaded portion of the bone pin includes a first setof upper threads and a smooth, non-threaded portion disposed above thefirst set of upper threads.
 3. The system of claim 2, wherein the pitchof the first set of upper threads is lower than the pitch of the lowerthreaded portion.
 4. The system of claim 2, wherein the upper threadedportion of the bone pin includes a second set of upper threads disposedabove the non-threaded portion.
 5. The system of claim 4, wherein thepitch of the first and second sets of upper threads is substantially thesame.
 6. The system of claim 1, wherein the pitch of the upper threadedportion is lower than the pitch of the lower threaded portion, and adiameter of the flange is higher than the diameter of the lower threadedportion.
 7. The system of claim 1, further comprising a locking nutsized to be threadably receive the upper threaded portion.
 8. The systemof claim 7, wherein the locking nut includes a circumferential flange.9. The system of claim 1, wherein the distraction blade includes apartially open ring for receiving the bone pin.
 10. The system of claim9, wherein: the locking nut includes a circumferential flange; and thefirst distraction blade includes a laterally open ring for receiving thebone pin therein and for supporting the locking nut flange.
 11. A tissuedistraction system comprising: a distraction blade configured todistract tissue; a bone pin including: a lower threaded portion adaptedto be rotationally driven into a vertebral body; a flange disposed abovethe lower threaded portion and adapted to support the distraction blade,the flange having a larger diameter than the lower threaded portion; anupper threaded portion disposed above the flange, wherein thedistraction blade is adapted to be delivered over the bone pin andshaped to rest on the flange; a retractor frame having an adjustable armadapted to grip the distraction blade.
 12. The system of claim 11,wherein the upper threaded portion of the bone pin includes a first setof upper threads and a smooth, non-threaded portion disposed above thefirst set of upper threads.
 13. The system of claim 12, wherein thepitch of the first set of upper threads is lower than the pitch of thelower threaded portion.
 14. The system of claim 12, wherein the upperthreaded portion of the bone pin includes a second set of upper threadsdisposed above the non-threaded portion.
 15. The system of claim 14,wherein the pitch of the first and second sets of upper threads issubstantially the same.
 16. The system of claim 11, wherein the pitch ofthe upper threaded portion is lower than the pitch of the lower threadedportion.
 17. The system of claim 11, further comprising a locking nutsized to be threadably receive the upper threaded portion.
 18. Thesystem of claim 17, wherein the locking nut includes a circumferentialflange.
 19. The system of claim 11, wherein the distraction bladeincludes a partially open ring for receiving the bone pin.
 20. Thesystem of claim 19, wherein: the locking nut includes a circumferentialflange; and the first distraction blade includes a laterally open ringfor receiving the bone pin therein and for supporting the locking nutflange.